The present technology relates to a zoom lens and an image pickup apparatus. More particularly, the present technology relates to a technical field of a zoom lens which has a zoom ratio of approximately 3 to 8 times and an angle of view at a wide angle end of approximately 55° to 80° and is suitable for use with a digital video camera, a digital still camera and so forth, and an image pickup apparatus which includes the zoom lens.
In recent years, along with the popularization of an image pickup apparatus which uses a solid-state image pickup device such as a digital video camera or a digital still camera, still higher picture quality is demanded. Especially, in order to obtain a rich gradation representation or a representation which takes advantage of blurring in a picked up image, a bright lens compatible with a still greater image pickup device is demanded.
In general, the lens size increases by increase of the image circle or the aperture of the lens. However, also miniaturization of the lens with the portability taken into consideration is demanded strongly.
Meanwhile, in order to achieve compatibility between high quality and quietness upon zooming or focusing in moving picture image pickup, a lens is demanded which includes a zooming mechanism or a focusing mechanism of high quality by which image shaking or image skipping is less likely to be caused during image pickup.
In general, if the number of lens groups which move in a direction of an optical axis upon zooming or upon focusing is reduced to reduce the weight, then the compatibility between high quality and quietness upon zooming or upon focusing is facilitated.
A zoom lens suitable for use with a camera which uses an image pickup device of the APS-C size is known and disclosed in Japanese Patent Laid-Open No. 2011-247962 (hereinafter referred to as Patent Document 1). With the zoom lens, sufficient reduction in weight of a focusing group is achieved.
The zoom lens disclosed in Patent Document 1 includes a first lens group having a positive refracting power, a second lens group having a negative refracting power, a third lens group having a positive refracting power, a fourth lens group having a negative refracting power and a fifth lens group, disposed in order from the object side.
Another zoom lens by which compatibility between high quality and quietness upon zooming or upon focusing can be achieved readily is disclosed in Japanese Patent Laid-Open No. 2010-185942 (hereinafter referred to as Patent Document 2). The zoom lens is of the inner zoom type and the inner focus type in which the overall length of the optical system does not vary upon zooming and upon focusing.
The zoom lens disclosed in Patent Document 2 includes a first lens group having a positive refracting power, a second lens group having a negative refracting power, a third lens group having a positive refracting power, a fourth lens group having a positive refracting power and a fifth lens group having a positive refracting power, disposed in order from the object side.